Telephone electrically-driven sound box



Jan. 3, l19,28. 1,654,835

H. ROBECK TELEPHONE ELECTRICALLY DRIVEN SOUND B0X Filed Sept. 5, 1925 2Sheeles--Shemt 1 Figi F192.

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Jan. 3, 1928.

H`. ROBECK TELEPHONE ELECTRICALLY DRIVEN SOUND BOX Filed Sept. 5, 1925 2Sheets-Sheet 2 /n vento/1:

.sound box provided withthe throughout the several views.

Patented Jan. 3, 41928.

UNITED s'iaxrlz-sv lPATENT OFFICE.

TELEPHONE ELncrnrcArLY-nnrvnx soUN'n nox.-

Application led September 5, 1925, Serial No. 54,808, and in GermanyApril (25, 1925.

The subject matter of the present invention relates to that class oftelephone-electrically driven sound boxes being furnishedl rents, iswound in such a manner that the one stationary pole is strengthenedwhile the other one is weakened. In sound boxes of this kind. the anchoror pole being attached to the double armedlever of the sound box, mustbe heldin a ioatingstate between the stationary pole-shoes as otherwisea clean tune or sound cannot be p'roduced. f

In order tov attain this object the magnetsystem of each of the twostationary poles is, according to the present invention, ixed to anangular carrier, which has legs, which arescrewed to ears of the casingof the sound box; the bridge piece-of which carrier, supports themagnet-system and the pole-shoe, said shoe being screwed with its innerface to the bridge piece of the second carrier provided forthe secondstationary magnet-pole.

In the accompanying drawing the subject matter of the invention isrepresented by wayb an example in a special mode of construction.l

Fig. 1 is a central section through the' trical driving-means;

Fig. 2 is a front view of the sound box, the front stationary pole beingremoved;

Fig. 3 is a face orf/front view of a pole Fig. 4 a side View thereof;Fig. 5 is a sectional view on line A-B ,of Fig. 2;

Fig. 9 is a side view of said box in which A pole shoes and magnets arethe stationary omitted.

Similar numerals refer to similar parts lAs will be seen from thedrawings the numeral 1 indicates the casing' of the sound box having adiaphragm 2, the central Dart of which is lconnected to the arm 3 havinga horizontal bend or bridge 4', which is pressed by means of springs,being adjustable by screws, against points 6 of the casing of the soundbox. The points 6 are in a common plane with diaphragm 2, so that thearm 3, together with the bridge 4, is enabled to be swung Aaround anaxis lying in the plane ofA the diaphragm v2 and exten-ding between theconnectionlines of the points 6. On the bridge 4 the arm 8, carrying-thearmature 7 is. fixed in such a manner that it l extends downward. Onboth sides of thearmature 7 the stationary vmagnet-poles 9 and 10-aresituated a slight distance apart from .said armature. and parallel toeach other. In order to secure the proper support and adjustment of saidstationary poles with relation to the armature and to the plane of thediaphragm 2 vof the sound boX the stationary 'poles arev shaped in themanner represented in Figs. 3 to 7. First of all for eachpole an angularcarrier 11* is provided having a web or'bridge l1 on the outer sides ofwhich the horse-shoe like magnets 12 are attached by means of screws 12,and a foot 13'V which can be secured to the foot 14 of* the casing bymeans of screws '14'.

ranged in spaced relation, a spacer 15 being arranged .between them asshown. Now the proper pole-pieces are erected on the horseshoe llikemagnet-body 12, which pole-pieces are formed of angular strips 18 ofsheet metal being arranged between two cheeks 16, 17. The rectangularlegs 19 of said poles are surrounded by the coils 20. Directly beforethe front faces of said coils the armature 7 of the lever 3, 4 of thesound box is situated. The front-faces of the feet 13 of themagnet-carrier are ground o tothe proper angle with relation to theinnerfaces of thewebs or bridges 11, so that by screwing said webs orbridges to the fitting faces of the f eet 14 of the-sound box casingvtheeffect will be obtained that the pole faces of thefstationary magnetsvare caused to lie ex, actly symmetrical in .relation to the plane ofthe sound box diaphragm and parallelto each other. In this manner theproper sup. porting of the armature between said pole faces is ensured,\even when"`the latter are situated Iaz very slight distance from eachother. In order to still permitof a slight adiustability between thearmature and the The foot 14 has on .its lower side a ground'iittingface. The carriers 11", are arplane of the diaphragm, if there should beTransversely through the bush 22 and a hole of the bar 21 a shaft 23extends which 1s provided with a milled cut out 24 which 'forms aneccentric cam. A leaf spring 25 pulls the bar 21 downward.- If thereforethe shaft 23 is turned, which may be elected by means of the handwheel26, the bar said leaf spring 21 will be .moved downward to the extentpermitted by the cam 24 under the action of 25. Hence the levers 3, 4, 8together with'y the armature 7 will be swung out in the samev extent. Bythese means a very exact and ne adjustmentbetwe'en the diaplhragm andthe armature with respect to t e stationary pole faces ofthe pole pieces9 and 1l) canbe obtained.

What I claim is 1. A- sound 'box operable by telephone electriccurrents, comprising a casing, a diaphragm therein, an angular leverhaving two arms, .one .of which is connected -to the diaphragm, anarmature carried by the other arm of the lever, fixed magnets havingpole piecesprsented to opposite sides of and in spaced relation to thearmature, windings on said pole pieces and means mounting the-last namedarm of said lever,` for adjust'- ment of said armature between said polepieces, and carriers, for said. magnets, each' comprising a bridge andmembers at an angle to said bridge, said brldges being arranged invspaced relation, and a spacer between and connect-ing said bridges,lsaid casing being secured directly on said members.

2. A sound 'box operable by telephoneA e arm of the lever, fixed magnetshaving pole pieces presented to opposite sides of and in spaced relationto the armature, windings on said pole pieces and means mounting thelast named arm of said lever fo1,adju'stment of, said armature betweensaid pole pieces, said mountingmeans comprising a spring active to movesaid lever arm in one direction, a shaft monted in the casing and hav#in" a cam and a connecting element between said arm and said shaft andarranged to c0` act with'said cani to adjust said lever arm and hencealso said armature against the action of said spring.

' In'testimony whereof have affixed my signature.

HERMANN RQBECK.

